1. Technical Field
One or more embodiments of the present invention relate to a driving force distribution control apparatus for a four-wheel drive vehicle.
2. Description of Related Art
In the background art, there is known a driving force distribution control apparatus provided with a clutch which can change distribution of a driving force to front wheels and rear wheels, and a controller which controls an engagement force of the clutch in accordance with a traveling state (for example, see Patent Document 1).
In the driving force distribution control apparatus disclosed in Patent Document 1, pre-torque T1 corresponding to a quantity of accelerator operation performed by a driver and ΔN torque T2 corresponding to a differential rotation frequency between the front wheels and the rear wheels are calculated, and a driving force is transmitted to the rear wheels (driven wheel side) through the clutch based on command torque T which is a summation of the pre-torque T1 and the ΔN torque T2.
The driving force distribution control apparatus also includes a different-diameter tire attachment determination unit which determines whether a different-diameter tire has been attached or not based on a difference in wheel speed between the front wheels and the rear wheels in a steady traveling state. When it is determined that a different-diameter tire has been attached, the clutch is controlled to prevent a driving force corresponding to the pre-torque T1 from being transmitted to the rear wheels. Thus, suppressed is a bad influence which may occur due to the clutch engaged in the state where the different-diameter tire has been attached.
Patent Document 1: JP-A-2004-90703